Infectious bio-aerosols: the example of influenza.

Associate Professor, University of Calgary

Some infectious agents can be acquired by inhalation of aerosol-sized particles ( < 5-10 ┬Ám); some infectious disease can be transmitted from an infected patient through generation of infectious aerosols, typically by coughing or sneezing. In this presentation the genesis of infectious bio-aerosols and the mechanism of infection acquisition through inhalation of bio-aerosols will be reviewed, with examples drawn from influenza including some of the evidence supporting a role for aerosol transmission of influenza. Basic properties of aerosol dispersion will be reviewed, as well as biological decay of infectivity in aerosolized influenza virus and its modulation by physical parameters including relative humidity. The concept of long range infection will be examined, including how it is affected by different parameters including ventilation, biological decay, viral load in the source host and the infectious dose required to initiate infection.

From an understanding of the physics and physiology of bio-aerosols follows some implication for minimizing aerosol transmission in buildings, which has implication, for example, for influenza control including in pandemic scenarios. Basic interventions include adequate ventilation, and control of the temperature and relative humidity; there is a regain of interest in upper room air decontamination through ultra-violet irradiation (UVC band). Interestingly, control measures could work synergistically.